1. Field of the Invention
Fields of the inventions are: Data Storage, Compact Disc, and Optical Storage
Fields of search are: 235/375, 462; 250/201.5; 350/166, 355, 356, 375, 381, 383, 385, 386, 387, 388, 392; 359/245, 248, 250, 276, 281; 360/18, 24, 32, 33.1, 39, 72.01, 72.02; 369/44.23, 44.41, 44.42, 44.37, 59, 102, 111, 112, 124, 275.1, 275.3,
2. Description of the Prior Art
Current optical disc data pickup systems employ an electro-mechanical gimbal optical system to track and read the data band spiral. These gimbal systems use a single diode laser. In the more conventional system the laser beam is diffracted into three beams. In this approach the center beam reads the data while the outer beams track the spiral. Tracking errors generated by the tracking beams produce a mechanical torque to swivel the optical system so as to bring the reading beam to the center of the data spiral.
Techniques are also known wherein the light probe employed to track and read the data band spiral is delivered to the surface of the disc by an optical fiber. In this approach the fiber is in a permanent magnet inside an electro-magnet. An electrical current in the electro-magnet causes the permanent magnet to move. This causes the fiber to move thus translating the light probe across the surface of the disc.
Techniques are known whereby a constructive interference fringe can be produced and its position controlled by an electric field:
3,506,334 Apr., 1970 A. Korpel 5,071,253 Dec., 1991 R. Chase
Techniques are known whereby digital data can be recorded on and read from an optical compact disc:
 5,587,983 Dec., 1996 J. Bailey 5,646,920 Jul., 1997 W. Raczynski